This invention relates to improving catalytic cracking operations for hydrocarbon-containing oils. In one aspect, the invention relates to an oil nozzle for a catalytic cracking unit. In another aspect the invention relates to a method for atomizing the feed to a catalytic cracking unit.
Catalytic cracking is one attractive method for upgrading heavy liquid hydrocarbon feedstocks to gasoline and other valuable products. Such catalytic cracking upgrading operations, however, have not always been completely satisfactory. In the cracking of heavy residual oils, for example, the depositing of large amounts of carbonaceous material, commonly referred to as coke, around the feed inlet can interfere with injecting the oil feed into the unit for contact with the cracking catalyst. Further difficulties are encountered in the catalytic cracking of slurry oils which contain catalyst particles where the nozzle can be eroded by contact with the flowing catalyst particles.
Rapid vaporization of the oil feed is critical for satisfactory operation of the cracking unit. Heavy oils and residual fractions are difficult to satisfactorily vaporize even when the injection equipment is functioning perfectly, and nozzle coking or erosion in such a manner that interferes with vaporization of the oil feed is clearly undesirable.
It is an object of this invention to provide a nozzle suitable for use in a catalytic cracking unit which provides good atomization of a heavy oil feed.
It is another object of this invention to provide an oil nozzle for a catalytic cracking unit which can be retractably positioned in the unit so that it is easily removed for maintenance, repair or replacement.
It is a further object of this invention to provide an oil nozzle for use in a catalytic cracking unit in which the oil spray is discharged parallel to the longitudinal axis of the nozzle.
It is another object of this invention to provide an oil nozzle for a catalytic cracking unit which is highly resistant to erosion damage and fouling by coking.
It is still another object of this invention to provide a method for atomizing an oil feedstock which mitigates eddy currents at the discharge end of the nozzle which can cause nozzle fouling or plugging by coke deposits and erosion damage.